Polyetherimide esters comprised of the reaction products of (a) a diol, (b) a dicarboxylic acid, (c) a poly(oxy alkylene)diamine, and (d) a tricarboxylic acid or its derivative are known and are described in U.S. Pat. Nos. 4,544,734 and 4,556,705 to McCready and in U.S. Pat. No. 4,556,688 to McCready et al. These polyetherimide esters exhibit excellent stress-strain properties, low tensile set, high melting temperatures and/or excellent strength/toughness characteristics as well as superior flexibility which are especially suitable for molding and extrusion applications.
It has now been discovered that by varying the diol reactant polyetherimide esters can be provided which exhibit high or improved tensile elongation. The polyetherimide esters exhibiting these high tensile elongation properties are obtained by utilizing as the diol reactant a mixture containing a butanediol and a butenediol.